/* * rtc-st-lpc.c - ST's LPC RTC, powered by the Low Power Timer * * Copyright (C) 2014 STMicroelectronics Limited * * Author: David Paris for STMicroelectronics * Lee Jones for STMicroelectronics * * Based on the original driver written by Stuart Menefy. * * This program is free software; you can redistribute it and/or * modify it under the terms of the GNU General Public Licence * as published by the Free Software Foundation; either version * 2 of the Licence, or (at your option) any later version. */ #include #include #include #include #include #include #include #include #include #include #include #include /* Low Power Timer */ #define LPC_LPT_LSB_OFF 0x400 #define LPC_LPT_MSB_OFF 0x404 #define LPC_LPT_START_OFF 0x408 /* Low Power Alarm */ #define LPC_LPA_LSB_OFF 0x410 #define LPC_LPA_MSB_OFF 0x414 #define LPC_LPA_START_OFF 0x418 /* LPC as WDT */ #define LPC_WDT_OFF 0x510 #define LPC_WDT_FLAG_OFF 0x514 struct st_rtc { struct rtc_device *rtc_dev; struct rtc_wkalrm alarm; struct resource *res; struct clk *clk; unsigned long clkrate; void __iomem *ioaddr; bool irq_enabled:1; spinlock_t lock; short irq; }; static void st_rtc_set_hw_alarm(struct st_rtc *rtc, unsigned long msb, unsigned long lsb) { unsigned long flags; spin_lock_irqsave(&rtc->lock, flags); writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF); writel_relaxed(msb, rtc->ioaddr + LPC_LPA_MSB_OFF); writel_relaxed(lsb, rtc->ioaddr + LPC_LPA_LSB_OFF); writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF); writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF); spin_unlock_irqrestore(&rtc->lock, flags); } static irqreturn_t st_rtc_handler(int this_irq, void *data) { struct st_rtc *rtc = (struct st_rtc *)data; rtc_update_irq(rtc->rtc_dev, 1, RTC_AF); return IRQ_HANDLED; } static int st_rtc_read_time(struct device *dev, struct rtc_time *tm) { struct st_rtc *rtc = dev_get_drvdata(dev); unsigned long lpt_lsb, lpt_msb; unsigned long long lpt; unsigned long flags; spin_lock_irqsave(&rtc->lock, flags); do { lpt_msb = readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF); lpt_lsb = readl_relaxed(rtc->ioaddr + LPC_LPT_LSB_OFF); } while (readl_relaxed(rtc->ioaddr + LPC_LPT_MSB_OFF) != lpt_msb); spin_unlock_irqrestore(&rtc->lock, flags); lpt = ((unsigned long long)lpt_msb << 32) | lpt_lsb; do_div(lpt, rtc->clkrate); rtc_time_to_tm(lpt, tm); return 0; } static int st_rtc_set_time(struct device *dev, struct rtc_time *tm) { struct st_rtc *rtc = dev_get_drvdata(dev); unsigned long long lpt; unsigned long secs, flags; int ret; ret = rtc_tm_to_time(tm, &secs); if (ret) return ret; lpt = (unsigned long long)secs * rtc->clkrate; spin_lock_irqsave(&rtc->lock, flags); writel_relaxed(lpt >> 32, rtc->ioaddr + LPC_LPT_MSB_OFF); writel_relaxed(lpt, rtc->ioaddr + LPC_LPT_LSB_OFF); writel_relaxed(1, rtc->ioaddr + LPC_LPT_START_OFF); spin_unlock_irqrestore(&rtc->lock, flags); return 0; } static int st_rtc_read_alarm(struct device *dev, struct rtc_wkalrm *wkalrm) { struct st_rtc *rtc = dev_get_drvdata(dev); unsigned long flags; spin_lock_irqsave(&rtc->lock, flags); memcpy(wkalrm, &rtc->alarm, sizeof(struct rtc_wkalrm)); spin_unlock_irqrestore(&rtc->lock, flags); return 0; } static int st_rtc_alarm_irq_enable(struct device *dev, unsigned int enabled) { struct st_rtc *rtc = dev_get_drvdata(dev); if (enabled && !rtc->irq_enabled) { enable_irq(rtc->irq); rtc->irq_enabled = true; } else if (!enabled && rtc->irq_enabled) { disable_irq(rtc->irq); rtc->irq_enabled = false; } return 0; } static int st_rtc_set_alarm(struct device *dev, struct rtc_wkalrm *t) { struct st_rtc *rtc = dev_get_drvdata(dev); struct rtc_time now; unsigned long now_secs; unsigned long alarm_secs; unsigned long long lpa; st_rtc_read_time(dev, &now); rtc_tm_to_time(&now, &now_secs); rtc_tm_to_time(&t->time, &alarm_secs); /* Invalid alarm time */ if (now_secs > alarm_secs) return -EINVAL; memcpy(&rtc->alarm, t, sizeof(struct rtc_wkalrm)); /* Now many secs to fire */ alarm_secs -= now_secs; lpa = (unsigned long long)alarm_secs * rtc->clkrate; st_rtc_set_hw_alarm(rtc, lpa >> 32, lpa); st_rtc_alarm_irq_enable(dev, t->enabled); return 0; } static struct rtc_class_ops st_rtc_ops = { .read_time = st_rtc_read_time, .set_time = st_rtc_set_time, .read_alarm = st_rtc_read_alarm, .set_alarm = st_rtc_set_alarm, .alarm_irq_enable = st_rtc_alarm_irq_enable, }; static int st_rtc_probe(struct platform_device *pdev) { struct device_node *np = pdev->dev.of_node; struct st_rtc *rtc; struct resource *res; struct rtc_time tm_check; uint32_t mode; int ret = 0; ret = of_property_read_u32(np, "st,lpc-mode", &mode); if (ret) { dev_err(&pdev->dev, "An LPC mode must be provided\n"); return -EINVAL; } /* LPC can either run as a Clocksource or in RTC or WDT mode */ if (mode != ST_LPC_MODE_RTC) return -ENODEV; rtc = devm_kzalloc(&pdev->dev, sizeof(struct st_rtc), GFP_KERNEL); if (!rtc) return -ENOMEM; spin_lock_init(&rtc->lock); res = platform_get_resource(pdev, IORESOURCE_MEM, 0); rtc->ioaddr = devm_ioremap_resource(&pdev->dev, res); if (IS_ERR(rtc->ioaddr)) return PTR_ERR(rtc->ioaddr); rtc->irq = irq_of_parse_and_map(np, 0); if (!rtc->irq) { dev_err(&pdev->dev, "IRQ missing or invalid\n"); return -EINVAL; } ret = devm_request_irq(&pdev->dev, rtc->irq, st_rtc_handler, 0, pdev->name, rtc); if (ret) { dev_err(&pdev->dev, "Failed to request irq %i\n", rtc->irq); return ret; } enable_irq_wake(rtc->irq); disable_irq(rtc->irq); rtc->clk = clk_get(&pdev->dev, NULL); if (IS_ERR(rtc->clk)) { dev_err(&pdev->dev, "Unable to request clock\n"); return PTR_ERR(rtc->clk); } clk_prepare_enable(rtc->clk); rtc->clkrate = clk_get_rate(rtc->clk); if (!rtc->clkrate) { dev_err(&pdev->dev, "Unable to fetch clock rate\n"); return -EINVAL; } device_set_wakeup_capable(&pdev->dev, 1); platform_set_drvdata(pdev, rtc); /* * The RTC-LPC is able to manage date.year > 2038 * but currently the kernel can not manage this date! * If the RTC-LPC has a date.year > 2038 then * it's set to the epoch "Jan 1st 2000" */ st_rtc_read_time(&pdev->dev, &tm_check); if (tm_check.tm_year >= (2038 - 1900)) { memset(&tm_check, 0, sizeof(tm_check)); tm_check.tm_year = 100; tm_check.tm_mday = 1; st_rtc_set_time(&pdev->dev, &tm_check); } rtc->rtc_dev = rtc_device_register("st-lpc-rtc", &pdev->dev, &st_rtc_ops, THIS_MODULE); if (IS_ERR(rtc->rtc_dev)) { clk_disable_unprepare(rtc->clk); return PTR_ERR(rtc->rtc_dev); } return 0; } static int st_rtc_remove(struct platform_device *pdev) { struct st_rtc *rtc = platform_get_drvdata(pdev); if (likely(rtc->rtc_dev)) rtc_device_unregister(rtc->rtc_dev); return 0; } #ifdef CONFIG_PM_SLEEP static int st_rtc_suspend(struct device *dev) { struct st_rtc *rtc = dev_get_drvdata(dev); if (device_may_wakeup(dev)) return 0; writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF); writel_relaxed(0, rtc->ioaddr + LPC_LPA_START_OFF); writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF); return 0; } static int st_rtc_resume(struct device *dev) { struct st_rtc *rtc = dev_get_drvdata(dev); rtc_alarm_irq_enable(rtc->rtc_dev, 0); /* * clean 'rtc->alarm' to allow a new * .set_alarm to the upper RTC layer */ memset(&rtc->alarm, 0, sizeof(struct rtc_wkalrm)); writel_relaxed(0, rtc->ioaddr + LPC_LPA_MSB_OFF); writel_relaxed(0, rtc->ioaddr + LPC_LPA_LSB_OFF); writel_relaxed(1, rtc->ioaddr + LPC_WDT_OFF); writel_relaxed(1, rtc->ioaddr + LPC_LPA_START_OFF); writel_relaxed(0, rtc->ioaddr + LPC_WDT_OFF); return 0; } #endif static SIMPLE_DEV_PM_OPS(st_rtc_pm_ops, st_rtc_suspend, st_rtc_resume); static const struct of_device_id st_rtc_match[] = { { .compatible = "st,stih407-lpc" }, {} }; MODULE_DEVICE_TABLE(of, st_rtc_match); static struct platform_driver st_rtc_platform_driver = { .driver = { .name = "st-lpc-rtc", .pm = &st_rtc_pm_ops, .of_match_table = st_rtc_match, }, .probe = st_rtc_probe, .remove = st_rtc_remove, }; module_platform_driver(st_rtc_platform_driver); MODULE_DESCRIPTION("STMicroelectronics LPC RTC driver"); MODULE_AUTHOR("David Paris "); MODULE_LICENSE("GPL");